Secretary of State Rex Tillerson used a secondary email address under the name Wayne Tracker to send and receive information about climate change and other topics during his tenure at Exxon Mobil, according to the New York State Attorney General's Office.

Exxon Mobil confirmed the secondary email account and stressed that it was not used exclusively for climate change matters, saying in a statement it was used for "a broad range of business-related topics."

Company spokesman Alan Jeffers said the account was "mostly used while he [Tillerson] was traveling to ensure he'd see an item in a secure and timely way without having to sort through his regular email inbox, which could contain many items. To suggest it was exclusively or even primarily about climate issues is absolutely false and misleading."

The state attorney general's office discovered the Wayne Tracker account during an investigation of Exxon Mobil to determine whether the company misled shareholders and the public about possible financial risks that climate change poses to its business.

The investigation began in November 2015, and on Monday the attorney general's office sent a letter to New York County Supreme Court saying Exxon Mobil "has failed to comply in good faith" with a subpoena issued to produce documents from the company's top executives, including from the Wayne Tracker email account.

"Despite the company's incidental production of approximately 60 documents bearing the 'Wayne Tracker' email address, neither Exxon nor its counsel have ever disclosed that this separate email account was a vehicle for Mr. Tillerson's relevant communications at Exxon, and no documents appear to have been collected from this email account, which also does not appear on Exxon's list of preserved custodial sources or its privilege logs," the letter reads.

The letter also says there are "34 additional email accounts specifically assigned to top executives, board members or their assistants" that were not initially produced in the investigation.

Exxon Mobil said in a statement that the company "has been responsive … and has provided more than 2.5 million pages of documents."

"Media reports indicating that emails to or from this address were exclusively for climate-related topics are false," the statement said. "The very fact the attorney general's office has these emails is because they were produced in response to the subpoena."

It continued, "Rex Tillerson's main email address received a large volume of messages from a variety of internal and external sources. The email address Wayne.Tracker@exxonmobil.com is part of the company's email system and was put in place for secure and expedited communications between select senior company officials and the former chairman for a broad range of business-related topics."

It is not unheard of for business executives to maintain alias email accounts for inner circle communications.

The company also said it "believes the risk of climate change is clear and warrants action."

Tillerson's middle name is Wayne, but the company did not explain the origin of the name Wayne Tracker.

"I'm not sure how the name was chosen," Jeffers told ABC News in an email.

After a four-decade career at the company, Tillerson, 64, left this year to become President Trump's secretary of state. He had been Exxon Mobil's chairman and CEO since 2006.

The news of the secondary email account has raised questions among climate advocacy groups.

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